packet.go

package rtcp

// Packet represents an RTCP packet, a protocol used for out-of-band statistics and control information for an RTP session
type Packet interface {
	Header() Header
	// DestinationSSRC returns an array of SSRC values that this packet refers to.
	DestinationSSRC() []uint32

	Marshal() ([]byte, error)
	Unmarshal(rawPacket []byte) error
}

// unmarshal is a factory which pulls the first RTCP packet from a bytestream,
// and returns it's parsed representation, and the amount of data that was processed.
func unmarshal(rawData []byte) (packet Packet, bytesprocessed int, err error) {
	var h Header

	err = h.Unmarshal(rawData)
	if err != nil {
		return nil, 0, err
	}

	bytesprocessed = int(h.Length+1) * 4
	inPacket := rawData[:bytesprocessed]

	switch h.Type {
	case TypeSenderReport:
		packet = new(SenderReport)

	case TypeReceiverReport:
		packet = new(ReceiverReport)

	case TypeSourceDescription:
		packet = new(SourceDescription)

	case TypeGoodbye:
		packet = new(Goodbye)

	case TypeTransportSpecificFeedback:
		switch h.Count {
		case FormatTLN:
			packet = new(TransportLayerNack)
		case FormatRRR:
			packet = new(RapidResynchronizationRequest)
		default:
			packet = new(RawPacket)
		}

	case TypePayloadSpecificFeedback:
		switch h.Count {
		case FormatPLI:
			packet = new(PictureLossIndication)
		case FormatSLI:
			packet = new(SliceLossIndication)
		case FormatREMB:
			packet = new(ReceiverEstimatedMaximumBitrate)
		default:
			packet = new(RawPacket)
		}

	default:
		packet = new(RawPacket)
	}

	err = packet.Unmarshal(inPacket)

	return packet, bytesprocessed, err
}